Special Purpose Objects Introduction

There are three INT special purpose objects . There are coding examples below for the two more complex objects, ViewPort and Wavelet. The third special purpose object, the Crop object is almost identical to the Image object in INT's graphics library.

ViewPort Coding Example

The following code sample illustrates how to use the ViewPort object class to zoom a contour widget which contains a number of Graphic objects. See basemap_demo.c in the demos directory for the complete code.

First define the data types needed.

    Widget contour, contour_zoom;
    Object *obj_list;
    int    object_count;
    int    x, y, width, height;

Next, create a zoom of the contour widget.

    contour_zoom = (Widget) XintContourZoom(contour, parent, cb, 2.5, 2.5);
    x      = cb->x_start;
    y      = cb->y_start;
    width  = cb->x_end - x;
    height = cb->y_end - y;

    /*Where cb is a pointer to an XintGridAreaSelectionCallbackStruct 
      structure which defines the area to be zoomed. */

Now retrieve a list of the objects that intersect with the given rectangle.

    obj_list = XintEditObjectGetIntersectList(contour, x, y, width, height,
                                              &object_count);

Then create a ViewPort object for each object in the list. Afterward the list can be freed.

    for (i=0; i<object_count; i++) 
         XtVaCreateWidget("vp", (WidgetClass) xintViewPortObjectClass, 
                          contour_zoom, XmNobject, obj_list[i], NULL);

    XtFree((char *) obj_list);